Microchip manufacturers deposit various material layers on a wafer during microchip processing. At certain stages, a photosensitive resist (hereinafter “photoresist”) may be deposited on one or more layers. A lithography tool may transmit light to a reticle which has a pattern. Light from the reticle transfers the pattern onto the photoresist and causes a chemical reaction, e.g., solubility change, in the exposed areas of the photoresist. The solubility change is used to selectively remove exposed areas of the photoresist, which leaves a three-dimensional relief image in the photoresist. Portions of the underlying layer which are not protected by the remaining photoresist may undergo further processing, such as etching or ion implantation to form integrated circuit features.
The semiconductor industry has reduced the size of transistor features to increase transistor density and improve transistor performance. The benefits of reducing transistor feature size have driven a reduction in the wavelength of light used in lithography tools in order to define smaller transistor features on a photoresist.